In recent years, there has been increasing use of composite materials in aircraft structures, including the air frame structure, wings, rudder assemblies and skin panels. These composites are generally lightweight and therefore provide an opportunity to design lighter aircraft that have may have either a longer range or a greater payload, depending upon design criteria.
Composites generally include reinforcing filler encapsulated in a resin. The filler material may be fibers, particulates woven fabrics, or may be present in any other appropriate shape and form. The filler material may vary, and may include for example carbon fiber, graphite, fiber glass, and other appropriate materials. The resins may include for example the family of thermoplastic or thermosetting resins such as epoxy, phenolic, polyester, polyimide and other suitable engineering resins.
Composites generally are not electrically conductive. Accordingly, when composites are used as external skin panels on aircraft, the composites are sometimes metallized by the addition of a thin layer or coating of metal to the skin panel exterior surface. Typically, in aerospace the metal coating is aluminum because of its lightweight and electrical conductivity, although other metals may also be used. This metallization of the exterior composite skin panel surface shields a composite aircraft's internal electronic components from electromagnetic interference, and protects the aircraft during lightning storms.
Accordingly, it is desirable to develop processes for coating composite and other aircraft skin panels with a substantially uniform, metallic coating and for repairing metallic coatings of previously metallized aircraft skin panels. In addition, it is desirable that the coating is tightly-adhered to the aircraft skin panels. Other desirable features and characteristics of a process for making metallized skin panels include a capability to utilize existing coating equipment, and adaptability to coating a variety of shapes and sizes of composite and other substrates. Other features of the metallized composite, or other, skin panels and methods will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.